Infant Mortality And Air Pollution

March 27, 2000

What is the cost in human lives of air pollution? In particular, does it have a discernible effect on mortality in vulnerable populations -- newborns and infants? Researchers studied differences in infant mortality rates across a number of U.S. counties during the 1981-82 recession -- when the output of air pollution was less than before the recession or after the recovery.

They found that in the narrow period of 1980-82, there was substantial variation across counties in changes in particulates pollution, and that these differential pollution reductions appear to be related to changes in a multitude of other factors that may be related to infant mortality.

Using the most detailed and comprehensive data available, they found that a reduction of one milligram per cubic meter in particulates (a 1 mg/m3 reduction) results in about 4-8 fewer infant deaths per 100,000 live births at the county level.

The estimated effects are driven almost entirely by fewer deaths occurring within one month and one day of birth, suggesting that fetal exposure to pollution has adverse health consequences.

The estimated effects of the pollution reductions on infant birth weight provide evidence consistent with this potential pathophysiologic mechanism. The estimates are remarkably stable across a variety of circumstances, say the researchers.

Source: Kenneth Y. Chay and Michael Greenstone, "The Impact of Air Pollution on Infant Mortality: Evidence from Geographic Variation in Pollution Shocks Induced by a Recession," NBER Working Paper No. W7442, December 1999, National Bureau of Economic Research.